This invention relates to storing data by means of a digital print head and in particular storing the identification of digital print heads, for example thermal print heads or ink jet print heads, used in printing apparatus.
Digital print heads include a plurality of selectively operable printing elements. Commonly the printing elements are disposed in a line. The digital print head is mounted in printing apparatus and either the print head is moved relative to a print receiving medium or a print receiving medium is moved relative to the print head such that the print receiving medium is scanned by the print head. During the movement of the print head or the medium, the printing elements are operated selectively and successively in a plurality of print cycles to print dots that form desired characters or patterns on the print receiving medium.
The printing apparatus in which the print head is mounted may be a computer output printer or may be part of a postage meter for printing postage indicia on mail items.
Sometimes it is important, particularly in relation to postage meters and similar secure printing apparatus, to ensure that only an identified print head is utilised in the printing apparatus. Accordingly in order to ensure that only identified print heads are utilised in the printing apparatus it is necessary to provide the print head with means whereby the print head can be identified.
According to one aspect of the invention a method of registering data in relation to a digital print head having a plurality of selectively energisable printing elements comprises the steps of allocating first printing elements of said plurality of printing elements for representing data and altering a characteristic of selected first printing elements to represent said data.
According to a second aspect of the invention a method of registering data in relation to a digital print head having a plurality of selectively energisable print elements comprises the steps of allocating first printing elements of said plurality of printing elements for representing data; allocating second printing elements of said plurality of printing elements for printing required impressions and altering a characteristic of selected first printing elements to represent said data.
According to a third aspect of the invention printing apparatus includes a digital print head having a plurality of printing elements, first elements of said plurality of printing elements being allocated for normal printing of printed impressions and second elements of said plurality of elements being allocated for representing data; and data writing means operable to change an electrical characteristic of selected second elements to represent said data.
The printing apparatus may be postage indicia printer of a postage meter.